Preliminary results with a coupled global-limited-area analysis system for the time and region of the T-PARC/TCS-08 Field Program

This paper presents our first results on the analysis and forecast effects of observations collected in THORPEX Pacific Asian Regional Campaign/Tropical-Cyclone Structure-2008 (T-PARC/TCS-08) field program for a coupled global-limited-area analysis system. The data assimilation system used in this study is the Local Ensemble Transform Kalman Filter (LETKF), the global model is the model component of the Global Forecast System (GFS) of NCEP, and the regional model is the Regional Spectral Model of NCEP. The limited-area domain covers the parts of Eastern Asia and the western Nort-Pacific where T-PARC/TCS-08 took part. We use four different strategies to couple the global and the limited-area data assimilation systems. In three of the four strategies, information is propagated from the global to the limited area system. In the fourth strategy, information from the limited area domain is also propagated back from the limited-area to the global analysis system. Experiments are carried out at different resolutions of both models.